The pathophysiology of venous hypertensive myelopathy--study of an animal model: laboratory investigation.

OBJECT: The authors undertook this study to establish an animal model to investigate the pathophysiological changes of venous hypertensive myelopathy (VHM).

METHODS

This study was a randomized control animal study with blinded evaluation. The VHM model was developed in 24 adult New Zealand white rabbits by means of renal artery and vein anastomosis and trapping of the posterior vena cava; 12 rabbits were subjected to sham surgery. The rabbits were investigated by spinal function evaluation, abdominal aortic angiography, spinal MRI, and pathological examination of the spinal cord at different follow-up stages.

RESULTS

Twenty-two (91.67%) of 24 model rabbits survived the surgery and postoperative period. The patency rate of the arteriovenous fistula was 95.45% in these 22 animals. The model rabbits had significantly decreased motor and sensory hindlimb function as well as abnormalities at the corresponding segments of the spinal cord. Pathological examination showed dilation and hyalinization of the small blood vessels, perivascular and intraparenchymal lymphocyte infiltration, proliferation of glial cells, and neuronal degeneration. Electron microscopic examination showed loose lamellar structure of the myelin sheath, increased numbers of mitochondria in the thin myelinated fibers, and pyknotic neurons.

CONCLUSIONS

This model of VHM is stable and repeatable. Exploration of the sequential changes in spinal cord and blood vessels has provided improved understanding of this pathology, and the model may have potential for improving therapeutic results.